How far is the fast charge of "5 minutes of charging and 500 kilometers of battery life"?

In the same place, I like to advertise my "charge 30 minutes, battery life XXX kilometers" (where the XXX generation refers to a three-digit number that is uncertain but must be exaggerated), it seems that 30 minutes is a life and death line that must be observed at all times. The degree is comparable to OPPO's "charging for 5 minutes, talking for 2 hours."

Not to mention whether such slogans are rigorous and credible, but the slow charging of electric vehicles is indeed a very annoying thing. Even if one day the production car can do "charge for half an hour, battery life 300 kilometers", the time cost of charging a single battery is much greater than adding a box of oil. So, the question is, is the charging speed of the electric car so slow? Or what are the factors that limit the charging speed?

According to the old rules, today's article is still divided into four parts:

Part1: How fast is it called fast charge? What is the standard?

Part2: How do I know how long it takes for my electric car to be full?

Part3: What is the charging speed?

Part4: How can I "charge for 5 minutes and last for 500 kilometers"?

The author reminds: This article is slightly longer, and it needs to be better used with melon seeds and beverages. Are you ready? Part1 is coming!

Part1: How fast is it called fast charge? For the time being, "30 minutes charge 80%" shall prevail!

Before starting today's discussion, let me ask you a question: In your opinion, how fast is the electric car charging speed, can it be called fast charge? Tell me what you think in the comments section, I will send a small gift to the most serious partner.

Just like a mobile phone, how fast is an electric car charging fast? 1 hour full? Still 20% full for 20 minutes?

To discuss "how fast is fast", we need to clarify what is our basic appeal for charging?

1. Charge quickly, preferably as fast as refueling (fast)

2. Do not affect my battery life (do not hurt the battery)

3. Save as much money as possible. How much electricity is charged by the charger, how much electricity is charged by my battery pack (high conversion rate)

So how fast can you call it fast? Looking through the information, I found that the state has no hard rules. It is no wonder that the major manufacturers dare to blow the big blows during the propaganda.

From the propaganda of most electric vehicles, everyone has generally taken the "30 minutes charging 80%" as the propaganda gimmick, then let's think that the passenger car charges 80% in 30 minutes, and 160% in one hour is electric car fast. Filling the entry-level reference value, the charging rate is also 160% / 100% C = 1.6C. According to this standard, the publicity for 15 minutes is 80%, and the charging rate is 3.2C.

To be honest, according to our own algorithm, the charging rate of 3.2C is already very high. It takes 80 minutes to charge 80% of the electricity. The time spent on the time spent in the queue is not much different. If you charge the object for charging, SLA ModelSP100D, 15 minutes to supplement the cruising range is enough for you to travel to and from Beijing and Tianjin 2 趟.

Part2: How do I know how long it takes for my electric car to be full?

As soon as I picked up my iPhone 6 (which is really poor, I have no money to change), I can roughly estimate how long it will take to fill it. So how do you roughly estimate the charging time of an electric car?

The formula is very simple. If you don't know, go back and read the junior high school physics textbook and think about it for 1 minute: battery energy (kWh) / charging power (kW) = time (h)

Let's take the Tesla P100D (battery pack energy 100kWh, officially claimed cruising range 632km) as an example. When using different charging devices, it will take a long time to fill:

It can be seen that as the charging power increases, the equipment we use is getting bigger and bigger and more professional. From this we can see a problem: no diamonds, no porcelain. In order to charge quickly, the three parties involved in charging: battery, charging configuration, power distribution cannot run.

Part3: What is the charging speed?

To answer this question, we have to recall what we need to complete the charging: first you have to have a battery then you have to have a charger. It’s not enough to have these two. If there are no distributions at all levels of the State Grid, it’s all about empty talk. OK, the three things that affect the charging speed are the battery itself, the charging configuration and the distribution network.

Let's say one by one, let's talk about charging settings first.

First, Charging and distribution network

1 commercial DC fast charge speed is already good, but still need to go further!

Discussing fast charging, the easiest thing to think about is whether the battery can support fast charging. In fact, before the battery, I hope that everyone understands the importance of charging equipment and distribution network. Simply put, the higher the output power of the charging post, the smaller the battery capacity, and the shorter the charging time. This is the same as having to fill a pool with water. The larger the discharge pipe, the smaller the pool and the shorter the time is. However, we all hope that the battery capacity of our car is large enough, and the power required to charge will be doubled. Is this idea realistic? Let's take the industry-leading Tesla as an example. It provides users with a charging device called “Super Charging Pile”.

Tesla's super-charged pile is something that looks like a tanker.

The charging power of the Tesla super charging pile is 120kW, and the P100D full of 100kWh takes about 1 hour; if we ask the Tesla ModelSP100D to "fill 80% for 30 minutes", that is, 1.6C rate, then the charging The power should reach 320kW, which is much higher than the charging power that the charging pile can provide. In other words, it is almost impossible to complete the 80% of the 1.6C or 30 minutes for a fast charging pile such as Tesla “Super Charging Pile”, especially for those long-life pure electric vehicles. .

So, what is the concept of a 120kW super-charged pile for the distribution network?

The maximum power of a microwave oven that can be cooked like this can be cooked up to about 1 kW (some can reach 1.3-1.5 kW).

The maximum load of a normal household meter is about 6-10 kW (actually 6 kW is already very large), and the power of a Tesla + super charging pile is roughly equivalent to the total power of all the appliances in 15 ordinary households.

A Tesla super-charged pile is roughly equivalent to the total power of more than 1200 household microwave ovens and more than a dozen ordinary household appliances. In order to meet the normal operation of this super-charged pile, it is necessary for the State Grid to set a separate 10kV voltage device for it.

However, the distribution quota of a region is limited. There is not necessarily a margin for you to add a 10kV transformer. It is not good to save money, unless the entire area (that is, the cell to the main transformer station) is modified. Therefore, the state simply stipulates that private power stations are not allowed to be installed in civilian power grids. This is why most communities refuse to install high-power and fast-filled piles of friends.

Property management inner OS: I am not too troublesome, but electricity is not enough!

2. Home exchange slow charge is true slow!

What is the charging efficiency of the household 220V AC outlet that everyone likes to hear? 220Vx10a=2200W=2.2kW, roughly equivalent to 1/55 of the Tesla super charging pile. From here, we can see that Tesla's so-called super-charged pile is a true super-charged pile, and the slow charging pile installed in everyone's home is a true and slow charging pile.

AC slow-filled piles only output electricity, and do not have a charging function, so a silver car charger next to the engine is needed to charge the battery pack.

Secondly, since most of the automotive motors use DC motors, and the charging piles output AC power, it is necessary to use a car charger to convert and charge the battery pack. It is designed to match the input power of the AC, if it matches. The power is low (unable to accept high input power), even if connected to a more powerful charging pile, the charging speed cannot be improved.

Second, The battery: there are conditions to eat, let's talk about the battery problem

With enough food, we can discuss how to eat faster. If you still remember the original battery principle of junior high school physics textbooks, then roughly understand what we will discuss next.

The essence of battery charging and discharging is the redox reaction. Even if the external charging conditions are perfected, it is limited by the rate of redox reaction.

The process of charging and discharging a battery is essentially a process of a series of redox reactions inside the battery. Taking the most popular ternary lithium battery as an example, the charging process is nothing more than the lithium ion is deintercalated from the positive electrode, enters the electrolyte, and is inserted into the negative electrode material to move into the negative electrode, and at the same time, excess electrons are moved to the negative electrode through the positive electrode and the external device.

That is to say, the faster the lithium ions are diffused, the faster the electrons move, the better the charge and discharge performance of the battery, and the various problems such as life and safety must be considered. Each structure associated with lithium ion diffusion motion—positive material, negative electrode material, electrolyte, and separator—can affect the charge and discharge performance of the battery. How to influence the specifics, we will use a paper to explain in detail in the future, and we will not talk about it here.

Part4: How can I do “charge 5 minutes, battery life 500 kilometers”?

It is not difficult to achieve "charging for 5 minutes and battery life of 500 kilometers". The key is to get the national grid (sufficient power), the power battery research institute (to study the battery with higher current charging and high safety), and the electric vehicle. Support from manufacturers (production of new technologies and low enough prices).

To sum up briefly, you must first have a battery that can withstand more charging efficiency. Secondly, the grid can keep up with the development of fast charging technology and provide enough power. Finally, you need to pray that one who doesn't like to make money or has earned enough money to produce this technology and the price is low enough. And all of this obviously needs a long way to go.

The page contains the contents of the machine translation.